[O]ne might ask why, in a galaxy of a few hundred billion stars, the aliens are so intent on coming to Earth at all. It would be as if every vertebrate in North America somehow felt drawn to a particular house in Peoria, Illinois. Are we really that interesting?

[T]here is little chance that aliens from two societies anywhere in the Galaxy will be culturally close enough to really 'get along.' This is something to ponder as you watch the famous cantina scene in Star Wars. ... Does this make sense, given the overwhelmingly likely situation that galactic civilizations differ in their level of evolutionary development by thousands or millions of years? Would you share drinks with a trilobite, an ourang-outang, or a saber-toothed tiger? Or would you just arrange to have a few specimens stuffed and carted off to the local museum?

[The Big Bang is] followed by what? By a dull-as-ditchwater expansion which degrades itself adiabatically until it is incapable of doing anything at all. The notion that galaxies form, to be followed by an active astronomical history, is an illusion. Nothing forms, the thing is as dead as a door-nail.

According to our ancient Buddhist texts, a thousand million solar systems make up a galaxy. … A thousand million of such galaxies form a supergalaxy. … A thousand million supergalaxies is collectively known as supergalaxy Number One. Again, a thousand million supergalaxy Number Ones form a Supergalaxy Number Two. A thousand million supergalaxy Number Twos make up a supergalaxy Number Three, and of these, it is stated in the texts that there are a countless number in the universe.

And beyond our galaxy are other galaxies, in the universe all told at least a hundred billion, each containing a hundred billion stars. Do these figures mean anything to you?

Beyond lonely Pluto, dark and shadowless, lies the glittering realm of interstellar space, the silent ocean that rolls on and on, past stars and galaxies alike, to the ends of the Universe. What do men know of this vast infinity, this shoreless ocean? Is it hostile or friendly–or merely indifferent?

By the data to date, there is only one animal in the Galaxy dangerous to man—man himself. So he must supply his own indispensable competition. He has no enemy to help him.

Changes, cyclic or otherwise, within the solar system or within our galaxy, would seem to be the easy and incontrovertible solution for everything that I have found remarkable in the stratigraphical record.

Each of the major sciences has contributed an essential ingredient in our long retreat from an initial belief in our own cosmic importance. Astronomy defined our home as a small planet tucked away in one corner of an average galaxy among millions; biology took away our status as paragons created in the image of God; geology gave us the immensity of time and taught us how little of it our own species has occupied.

Finally, from what we now know about the cosmos, to think that all this was created for just one species among the tens of millions of species who live on one planet circling one of a couple of hundred billion stars that are located in one galaxy among hundreds of billions of galaxies, all of which are in one universe among perhaps an infinite number of universes all nestled within a grand cosmic multiverse, is provincially insular and anthropocentrically blinkered. Which is more likely? That the universe was designed just for us, or that we see the universe as having been designed just for us?

For many years I have been a night watchman of the Milky Way galaxy.

Fractal geometry will make you see everything differently. There is a danger in reading further. You risk the loss of your childhood vision of clouds, forests, flowers, galaxies, leaves, feathers, rocks, mountains, torrents of water, carpet, bricks, and much else besides. Never again will your interpretation of these things be quite the same.

Galaxies themselves cannot close the Universe.

Humans everywhere share the same goals when the context is large enough. And the study of the Cosmos provides the largest possible context … . If a human disagrees with you, let him live. In a hundred billion galaxies, you will not find another … . If we are to survive, our loyalties must be broadened further, to include the whole human community, the entire planet Earth.

I believe that the human mind, or even the mind of a cat, is more interesting in its complexity than an entire galaxy if it is devoid of life.

I hope that in 50 years we will know the answer to this challenging question: are the laws of physics unique and was our big bang the only one? … According to some speculations the number of distinct varieties of space—each the arena for a universe with its own laws—could exceed the total number of atoms in all the galaxies we see. … So do we live in the aftermath of one big bang among many, just as our solar system is merely one of many planetary systems in our galaxy? (2006)

I think that the event which, more than anything else, led me to the search for ways of making more powerful radio telescopes, was the recognition, in 1952, that the intense source in the constellation of Cygnus was a distant galaxy—1000 million light years away. This discovery showed that some galaxies were capable of producing radio emission about a million times more intense than that from our own Galaxy or the Andromeda nebula, and the mechanisms responsible were quite unknown. ... [T]he possibilities were so exciting even in 1952 that my colleagues and I set about the task of designing instruments capable of extending the observations to weaker and weaker sources, and of exploring their internal structure.

I will give you a “celestial multiplication table.” We start with a star as the unit most familiar to us, a globe comparable to the sun. Then—
A hundred thousand million Stars make one Galaxy;
A hundred thousand million Galaxies make one Universe.
The figures may not be very trustworthy, but I think they give a correct impression.

If the expansion of the space of the universe is uniform in all directions, an observer located in anyone of the galaxies will see all other galaxies running away from him at velocities proportional to their distances from the observer.

If the resident zoologist of Galaxy X had visited the earth 5 million years ago while making his inventory of inhabited planets in the universe, he would surely have corrected his earlier report that apes showed more promise than Old World monkeys and noted that monkeys had overcome an original disadvantage to gain domination among primates. (He will confirm this statement after his visit next year–but also add a footnote that one species from the ape bush has enjoyed an unusual and unexpected flowering, thus demanding closer monitoring.)

If this book were to be dedicated to its first and chief encouragement is should probably salute starlight, insects, the galaxies, and the fossil plants and animals.

In a sense, the galaxy hardest for us to see is our own. For one thing, we are imprisoned within it, while the others can be viewed as a whole from outside… . Furthermore, we are far out from the center, and to make matters worse, we lie in a spiral arm clogged with dust. In other words, we are on a low roof on the outskirts of the city on a foggy day.

In design, people like Buckminster Fuller amazed me at the levels at which he could think. He could think molecularly. And he could think at the almost galactic scale. And the idea that somebody could actually talk about molecules and talk about buildings and structures and talk about space just amazed me. As I get older–I’ll be 60 next year–what I’ve discovered is that I find myself in those three realms too.

Individual dolphins and whales are to be given the legal rights of human individuals. … Research into communication with cetaceans is no longer simply a scientific pursuit…. We must learn their needs, their ethics, their philosophy, to find out who we are on this planet, in this galaxy.

It is unlikely that we will ever see a star being born. Stars are like animals in the wild. We may see the very young, but never their actual birth, which is a veiled and secret event. Stars are born inside thick clouds of dust and gas in the spiral arms of the galaxy, so thick that visible light cannot penetrate them.

Man is a little germ that lives on an unimportant rock ball that revolves about a small star at the outskirts of an ordinary galaxy. ... I am absolutely amazed to discover myself on this rock ball rotating around a spherical fire. It’s a very odd situation. And the more I look at things I cannot get rid of the feeling that existence is quite weird.

One of the wonders of this world is that objects so small can have such consequences: any visible lump of matter—even the merest speck—contains more atoms than there are stars in our galaxy.

Our sun is one of 100 billion stars in our galaxy. Our galaxy is one of billions of galaxies populating the universe. It would be the height of presumption to think that we are the only living things in that enormous immensity.

Picture yourself during the early 1920's inside the dome of the [Mount Wilson Observatory]. … [Milton] Humason is showing [Harlow] Shapley stars he had found in the Andromeda Nebula that appeared and disappeared on photographs of that object. The famous astronomer very patiently explains that these objects could not be stars because the Nebula was a nearby gaseous cloud within our own Milky Way system. Shapley takes his handkerchief from his pocket and wipes the identifying marks off the back of the photographic plate.
Of course, Hubble came along in 1924 and showed that it was just these Cepheid variable stars in the Andromeda Nebula which proved it was a separate galaxy system.

Recognize that the very molecules that make up your body, the atoms that construct the molecules, are traceable to the crucibles that were once the centers of high mass stars that exploded their chemically rich guts into the galaxy, enriching pristine gas clouds with the chemistry of life. So that we are all connected to each other biologically, to the earth chemically and to the rest of the universe atomically. That’s kinda cool! That makes me smile and I actually feel quite large at the end of that. It’s not that we are better than the universe, we are part of the universe. We are in the universe and the universe is in us.

Since as the Creation is, so is the Creator also magnified, we may conclude in consequence of an infinity, and an infinite all-active power, that as the visible creation is supposed to be full of siderial systems and planetary worlds, so on, in like similar manner, the endless Immensity is an unlimited plenum of creations not unlike the known Universe.… That this in all probability may be the real case, is in some degree made evident by the many cloudy spots, just perceivable by us, as far without our starry Regions, in which tho’ visibly luminous spaces, no one Star or particular constituent body can possibly be distinguished; those in all likelyhood may be external creation, bordering upon the known one, too remote for even our Telescopes to reach.

So the universe will continue to expand forever, and the galaxies will get farther and farther apart, and things will just die. That’s the way it is. It doesn't matter whether I feel lonely about it or not.

Telescopes are in some ways like time machines. They reveal galaxies so far away that their light has taken billions of years to reach us. We in astronomy have an advantage in studying the universe, in that we can actually see the past.
We owe our existence to stars, because they make the atoms of which we are formed. So if you are romantic you can say we are literally starstuff. If you’re less romantic you can say we’re the nuclear waste from the fuel that makes stars shine.
We’ve made so many advances in our understanding. A few centuries ago, the pioneer navigators learnt the size and shape of our Earth, and the layout of the continents. We are now just learning the dimensions and ingredients of our entire cosmos, and can at last make some sense of our cosmic habitat.

The alternative to the Big Bang is not, in my opinion, the steady state; it is instead the more general theory of continuous creation. Continuous creation can occur in bursts and episodes. These mini-bangs can produce all the wonderful element-building that Fred Hoyle discovered and contributed to cosmology. This kind of element and galaxy formation can take place within an unbounded, non-expanding universe. It will also satisfy precisely the Friedmann solutions of general relativity. It can account very well for all the facts the Big Bang explains—and also for those devastating, contradictory observations which the Big Bang must, at all costs, pretend are not there

The evidence at present available points strongly to the conclusion that the spirals are individual galaxies, or island universes, comparable with our own galaxy in dimension and in number of component units.
[Stating his conviction on the nature of nebulae during the Shapley-Curtis debate on 26 Apr 1920 to the National Academy of Sciences.]

The idea that we shall be welcomed as new members into the galactic community is as unlikely as the idea that the oyster will be welcomed as a new member into the human community. We're probably not even edible.

The next object which I have observed is the essence or substance of the Milky Way. By the aid of a telescope anyone may behold this in a manner which so distinctly appeals to the senses that all the disputes which have tormented philosophers through so many ages are exploded at once by the irrefragable evidence of our eyes, and we are freed from wordy disputes upon this subject, for the Galaxy is nothing else but a mass of innumerable stars planted together in clusters.

The universe contains vastly more order than Earth-life could ever demand. All those distant galaxies, irrelevant for our existence, seem as equally well ordered as our own.

The unprecedented identification of the spectrum of an apparently stellar object in terms of a large red-shift suggests either of the two following explanations.
The stellar object is a star with a large gravitational red-shift. Its radius would then be of the order of 10km. Preliminary considerations show that it would be extremely difficult, if not impossible, to account for the occurrence of permitted lines and a forbidden line with the same red-shift, and with widths of only 1 or 2 per cent of the wavelength.
The stellar object is the nuclear region of a galaxy with a cosmological red-shift of 0.158, corresponding to an apparent velocity of 47,400 km/sec. The distance would be around 500 megaparsecs, and the diameter of the nuclear region would have to be less than 1 kiloparsec. This nuclear region would be about 100 times brighter optically than the luminous galaxies which have been identified with radio sources thus far. If the optical jet and component A of the radio source are associated with the galaxy, they would be at a distance of 50 kiloparsecs implying a time-scale in excess of 105 years. The total energy radiated in the optical range at constant luminosity would be of the order of 1059 ergs.
Only the detection of irrefutable proper motion or parallax would definitively establish 3C 273 as an object within our Galaxy. At the present time, however, the explanation in terms of an extragalactic origin seems more direct and less objectionable.

The very closest stars would require many years to visit, even traveling at the speed of light, which is impossible according to Einstein's theory of relativity. Today's fastest spaceships would require 200,000 years to travel to Alpha Centauri, our closest bright star. The energy required to send a hundred colonists to another star, as Frank Drake has pointed out, would be enough to meet the energy needs of the entire United States over a human lifetime. And these estimates are regarding nearby stars. When we consider the distances across the entire galaxy, and between galaxies, interstellar travel seems absolutely untenable.

There is a point of view among astronomical researchers that is generally referred to as the Principle of Mediocrity. ... If the Sun and its retinue of worlds is only one system among many, then many other systems will be like ours: home to life. Indeed, to the extent that this is true, we should be prepared for the possibility that, even in the Milky Way galaxy, billions of planets may be carpeted by the dirty, nasty business known as life.

There is already overwhelming evidence that the visible matter within galaxies may account for less than 10 percent of the galaxies’ actual mass: the rest, not yet directly detectable by observers on the earth, is probably distributed within and around each galaxy.

These neutrino observations are so exciting and significant that I think we're about to see the birth of an entirely new branch of astronomy: neutrino astronomy. Supernova explosions that are invisible to us because of dust clouds may occur in our galaxy as often as once every 10 years, and neutrino bursts could give us a way to study them.

Walking home at night, I shine my flashlight up at the sky. I send billions of ... photons toward space. What is their destination? A tiny fraction will be absorbed by the air. An even smaller fraction will be intercepted by the surface of planets and stars. The vast majority ... will plod on forever. After some thousands of years they will leave our galaxy; after some millions of years they will leave our supercluster. They will wander through an even emptier, even colder realm. The universe is transparent in the direction of the future.

We are insignificant creatures on a small rock orbiting a very average star in the outer suburbs of one of a hundred thousand million galaxies.

We have simply arrived too late in the history of the universe to see this primordial simplicity easily ... But although the symmetries are hidden from us, we can sense that they are latent in nature, governing everything about us. That's the most exciting idea I know: that nature is much simpler than it looks. Nothing makes me more hopeful that our generation of human beings may actually hold the key to the universe in our hands—that perhaps in our lifetimes we may be able to tell why all of what we see in this immense universe of galaxies and particles is logically inevitable.

We live on an obscure hunk of rock and metal circling a humdrum sun, which is on the outskirts of a perfectly ordinary galaxy comprised of 400 billion other suns, which, in turn, is one of some hundred billion galaxies that make up the universe, which, current thinking suggests, is one of a huge number—perhaps an infinite number—of other closed-off universes. From that perspective, the idea that we’re at the center, that we have some cosmic importance, is ludicrous.

Were the succession of stars endless, then the background of the sky would present us an uniform luminosity, like that displayed by the Galaxy—since there could be absolutely no point, in all that background, at which would not exist a star. The only mode, therefore, in which, under such a state of affairs, we could comprehend the voids which our telescopes find in innumerable directions, would be by supposing the distance of the invisible background so immense that no ray from it has yet been able to reach us at all.

What intellectual phenomenon can be older, or more oft repeated, than the story of a large research program that impaled itself upon a false central assumption accepted by all practitioners? Do we regard all people who worked within such traditions as dishonorable fools? What of the scientists who assumed that the continents were stable, that the hereditary material was protein, or that all other galaxies lay within the Milky Way? These false and abandoned efforts were pursued with passion by brilliant and honorable scientists. How many current efforts, now commanding millions of research dollars and the full attention of many of our best scientists, will later be exposed as full failures based on false premises?

When the history of our galaxy is written, and for all any of us know it may already have been, if Earth gets mentioned at all it won’t be because its inhabitants visited their own moon. That first step, like a newborn’s cry, would be automatically assumed. What would be worth recording is what kind of civilization we earthlings created and whether or not we ventured out to other parts of the galaxy.

When they [radio astronomers] grew weary at their electronic listening posts. When their eyes grew dim with looking at unrevealing dials and studying uneventful graphs, they could step outside their concrete cells and renew their dull spirits in communion with the giant mechanism they commanded, the silent, sensing instrument in which the smallest packets of energy, the smallest waves of matter, were detected in their headlong, eternal flight across the universe. It was the stethoscope with which they took the pulse of the all and noted the birth and death of stars, the probe which, here on an insignificant planet of an undistinguishable star on the edge of its galaxy, they explored the infinite.

Who are we? We find that we live on an insignificant planet of a humdrum star lost between two spiral arms in the outskirts of a galaxy, tucked away in some forgotten corner of a universe in which there are far more galaxies than people.

Yet as I cast my eye over the whole course of science I behold instances of false science, even more pretentious and popular than that of Einstein gradually fading into ineptitude under the searchlight; and I have no doubt that there will arise a new generation who will look with a wonder and amazement, deeper than now accompany Einstein, at our galaxy of thinkers, men of science, popular critics, authoritative professors and witty dramatists, who have been satisfied to waive their common sense in view of Einstein's absurdities.